Friction characteristics between paper and steel roller under mixed lubrication

This article describes the new theoretical modeling of friction coefficient between uncoated paper-web (newsprint; for example) and steel roller. In the modeling, the paper base is approximated by the linear spring and the surface asperities are treated as rigid body based on the observation of web surface structure. Introducing the contact mechanics, the mixed friction coefficient is formulated theoretically for a wide range of roller surface velocity, in which the air film thickness between the web and roller is estimated based on the foil bearing model. In the experiments, the newsprint is used as uncoated paper-web. Euler's belt formula is applied to calculate the friction coefficient from the measured data of tension increase. The measurements are carried out by changing five design parameters such as web width, wrap angle, tension, roller diameter, and roller surface velocity. The measured results are compared with the predicted results to verify the applicability of the present theoretical model. Good agreements can be seen between the predicted and measured results.